Eliminate full copying/saving of item tags

This unnecessarily stores a hell of a lot of unneeded data and heavily accumulates the more versions the pipeline goes down to.

core/src/main/java/nl/matsv/viabackwards/api/rewriters/ItemRewriter.java

@@ -5,6 +5,7 @@ import nl.matsv.viabackwards.api.data.MappedItem;
 import org.jetbrains.annotations.Nullable;
 import us.myles.ViaVersion.api.minecraft.item.Item;
 import us.myles.ViaVersion.api.rewriters.IdRewriteFunction;
+import us.myles.viaversion.libs.opennbt.tag.builtin.ByteTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.CompoundTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.ListTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.StringTag;
@@ -33,38 +34,41 @@ public abstract class ItemRewriter<T extends BackwardsProtocol> extends ItemRewr
     public Item handleItemToClient(Item item) {
         if (item == null) return null;
 
-        CompoundTag tag = null;
+        CompoundTag display = null;
-        boolean textChanged = false;
         if (translatableRewriter != null
-                && item.getTag() != null && (tag = item.getTag().get("display")) != null) {
+                && item.getTag() != null && (display = item.getTag().get("display")) != null) {
             // Handle name and lore components
-            StringTag name = tag.get("Name");
+            StringTag name = display.get("Name");
             if (name != null) {
                 String newValue = translatableRewriter.processText(name.getValue()).toString();
-                if (name.getValue().equals(newValue)) {
+                if (!newValue.equals(name.getValue())) {
-                    textChanged = true;
+                    saveNameTag(display, name);
                 }
+
                 name.setValue(newValue);
             }
 
-            ListTag lore = tag.get("Lore");
+            ListTag lore = display.get("Lore");
             if (lore != null) {
+                ListTag original = null;
+                boolean changed = false;
                 for (Tag loreEntry : lore) {
                     if (!(loreEntry instanceof StringTag)) continue;
 
                     StringTag stringTag = (StringTag) loreEntry;
                     String newValue = translatableRewriter.processText(stringTag.getValue()).toString();
-                    if (stringTag.getValue().equals(newValue)) {
+                    if (!changed && !newValue.equals(name.getValue())) {
-                        textChanged = true;
+                        changed = true;
+                        original = lore.clone();
                     }
+
                     stringTag.setValue(newValue);
                 }
-            }
-        }
 
-        if (textChanged) {
+                if (changed) {
-            // Backup data for toServer
+                    saveLoreTag(display, original);
-            item.getTag().put(createViaNBT(item));
+                }
+            }
         }
 
         MappedItem data = mappedItemFunction.get(item.getIdentifier());
@@ -73,23 +77,19 @@ public abstract class ItemRewriter<T extends BackwardsProtocol> extends ItemRewr
             return super.handleItemToClient(item);
         }
 
-        // Backup data for toServer if not already done above
-        if (!textChanged) {
-            if (item.getTag() == null) {
-                item.setTag(new CompoundTag(""));
-            }
-            item.getTag().put(createViaNBT(item));
-        }
-
         // Set remapped id
         item.setIdentifier(data.getId());
 
         // Set custom name - only done if there is no original one
-        if (tag == null) {
+        if (item.getTag() == null) {
-            item.getTag().put(tag = new CompoundTag("display"));
+            item.setTag(new CompoundTag(""));
         }
-        if (!tag.contains("Name")) {
+        if (display == null) {
-            tag.put(new StringTag("Name", data.getJsonName()));
+            item.getTag().put(display = new CompoundTag("display"));
+        }
+        if (!display.contains("Name")) {
+            display.put(new StringTag("Name", data.getJsonName()));
+            display.put(new ByteTag(nbtTagName + "|customName"));
         }
         return item;
     }

core/src/main/java/nl/matsv/viabackwards/api/rewriters/ItemRewriterBase.java

@@ -5,10 +5,9 @@ import org.jetbrains.annotations.Nullable;
 import us.myles.ViaVersion.api.minecraft.item.Item;
 import us.myles.ViaVersion.api.rewriters.IdRewriteFunction;
 import us.myles.viaversion.libs.opennbt.conversion.builtin.CompoundTagConverter;
-import us.myles.viaversion.libs.opennbt.tag.builtin.ByteTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.CompoundTag;
-import us.myles.viaversion.libs.opennbt.tag.builtin.ShortTag;
+import us.myles.viaversion.libs.opennbt.tag.builtin.ListTag;
-import us.myles.viaversion.libs.opennbt.tag.builtin.Tag;
+import us.myles.viaversion.libs.opennbt.tag.builtin.StringTag;
 
 public abstract class ItemRewriterBase<T extends BackwardsProtocol> extends Rewriter<T> {
 
@@ -42,53 +41,42 @@ public abstract class ItemRewriterBase<T extends BackwardsProtocol> extends Rewr
     @Nullable
     public Item handleItemToServer(Item item) {
         if (item == null) return null;
-
+        if (toServerRewriter != null) {
-        CompoundTag tag = item.getTag();
+            item.setIdentifier(toServerRewriter.rewrite(item.getIdentifier()));
-        if (tag == null) {
-            if (toServerRewriter != null) {
-                item.setIdentifier(toServerRewriter.rewrite(item.getIdentifier()));
-            }
-            return item;
-        }
-
-        CompoundTag viaTag = tag.remove(nbtTagName);
-        if (viaTag != null) {
-            short id = (short) viaTag.get("id").getValue();
-            item.setIdentifier(id);
-
-            Tag dataTag = viaTag.get("data");
-            short data = dataTag != null ? (short) dataTag.getValue() : 0;
-            item.setData(data);
-
-            Tag amountTag = viaTag.get("amount");
-            byte amount = amountTag != null ? (byte) amountTag.getValue() : 1;
-            item.setAmount(amount);
-
-            CompoundTag extras = viaTag.get("extras");
-            if (extras != null) {
-                item.setTag(CONVERTER.convert("", CONVERTER.convert(extras)));
-            }
-        } else {
-            // Rewrite id normally
-            if (toServerRewriter != null) {
-                item.setIdentifier(toServerRewriter.rewrite(item.getIdentifier()));
-            }
         }
+        restoreDisplayTag(item);
         return item;
     }
 
-    protected CompoundTag createViaNBT(Item item) {
+    protected void saveNameTag(CompoundTag displayTag, StringTag original) {
-        CompoundTag tag = new CompoundTag(nbtTagName);
+        displayTag.put(new StringTag(nbtTagName + "|o" + original.getName(), original.getValue()));
-        tag.put(new ShortTag("id", (short) item.getIdentifier()));
+    }
-        if (item.getAmount() != 1) {
+
-            tag.put(new ByteTag("amount", item.getAmount()));
+    protected void saveLoreTag(CompoundTag displayTag, ListTag original) {
+        displayTag.put(new ListTag(nbtTagName + "|o" + original.getName(), original.getValue()));
+    }
+
+    protected void restoreDisplayTag(Item item) {
+        if (item.getTag() == null) return;
+
+        CompoundTag display = item.getTag().get("display");
+        if (display != null) {
+            // Remove custom name / restore original name
+            if (display.remove(nbtTagName + "|customName") != null) {
+                display.remove("Name");
+            } else {
+                restoreDisplayTag(display, "Name");
+            }
+
+            // Restore lore
+            restoreDisplayTag(display, "Lore");
         }
-        if (item.getData() != 0) {
+    }
-            tag.put(new ShortTag("data", item.getData()));
+
+    private void restoreDisplayTag(CompoundTag displayTag, String tagName) {
+        StringTag original = displayTag.remove(nbtTagName + "|o" + tagName);
+        if (original != null) {
+            displayTag.put(original);
         }
-        if (item.getTag() != null) {
-            tag.put(CONVERTER.convert("extras", CONVERTER.convert(item.getTag())));
-        }
-        return tag;
     }
 }

core/src/main/java/nl/matsv/viabackwards/api/rewriters/LegacyBlockItemRewriter.java

@@ -27,6 +27,7 @@ import us.myles.viaversion.libs.fastutil.ints.Int2ObjectOpenHashMap;
 import us.myles.viaversion.libs.gson.JsonElement;
 import us.myles.viaversion.libs.gson.JsonObject;
 import us.myles.viaversion.libs.gson.JsonPrimitive;
+import us.myles.viaversion.libs.opennbt.tag.builtin.ByteTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.CompoundTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.IntTag;
 import us.myles.viaversion.libs.opennbt.tag.builtin.StringTag;
@@ -98,14 +99,7 @@ public abstract class LegacyBlockItemRewriter<T extends BackwardsProtocol> exten
             return super.handleItemToClient(item);
         }
 
-        if (item.getTag() == null) {
-            item.setTag(new CompoundTag(""));
-        }
-
-        // Backup data for toServer
         short originalData = item.getData();
-        item.getTag().put(createViaNBT(item));
-
         item.setIdentifier(data.getId());
         // Keep original data if mapped data is set to -1
         if (data.getData() != -1) {
@@ -114,19 +108,25 @@ public abstract class LegacyBlockItemRewriter<T extends BackwardsProtocol> exten
 
         // Set display name
         if (data.getName() != null) {
-            CompoundTag tag = item.getTag().get("display");
+            if (item.getTag() == null) {
-            if (tag == null) {
+                item.setTag(new CompoundTag(""));
-                item.getTag().put(tag = new CompoundTag("display"));
             }
-            StringTag nameTag = tag.get("Name");
+
+            CompoundTag display = item.getTag().get("display");
+            if (display == null) {
+                item.getTag().put(display = new CompoundTag("display"));
+            }
+
+            StringTag nameTag = display.get("Name");
             if (nameTag == null) {
-                tag.put(nameTag = new StringTag("Name", data.getName()));
+                display.put(nameTag = new StringTag("Name", data.getName()));
+                display.put(new ByteTag(nbtTagName + "|customName"));
             }
 
             // Handle colors
             String value = nameTag.getValue();
             if (value.contains("%vb_color%")) {
-                tag.put(new StringTag("Name", value.replace("%vb_color%", BlockColors.get(originalData))));
+                display.put(new StringTag("Name", value.replace("%vb_color%", BlockColors.get(originalData))));
             }
         }
         return item;

core/src/main/java/nl/matsv/viabackwards/protocol/protocol1_12_2to1_13/packets/BlockItemPackets1_13.java

@@ -592,8 +592,8 @@ public class BlockItemPackets1_13 extends nl.matsv.viabackwards.api.rewriters.It
             if (display != null) {
                 StringTag name = display.get("Name");
                 if (name instanceof StringTag) {
-                    StringTag via = display.remove(extraNbtTag + "|Name");
+                    display.put(new StringTag(extraNbtTag + "|Name", name.getValue()));
-                    name.setValue(via != null ? via.getValue() : ChatRewriter.jsonTextToLegacy(name.getValue()));
+                    name.setValue(ChatRewriter.jsonTextToLegacy(name.getValue()));
                 }
             }
 
@@ -788,8 +788,8 @@ public class BlockItemPackets1_13 extends nl.matsv.viabackwards.api.rewriters.It
                 CompoundTag displayTag = (CompoundTag) display;
                 StringTag name = displayTag.get("Name");
                 if (name instanceof StringTag) {
-                    displayTag.put(new StringTag(extraNbtTag + "|Name", name.getValue()));
+                    StringTag via = displayTag.remove(extraNbtTag + "|Name");
-                    name.setValue(ChatRewriter.legacyTextToJson(name.getValue()).toString());
+                    name.setValue(via != null ? via.getValue() : ChatRewriter.legacyTextToJson(name.getValue()).toString());
                 }
             }